Use Oracle INSTR function to search for multiple strings

INSTR doesn't support regex ORs - you'd have to define INSTR function calls for each substring you want to check for. The equivalent of regexp_instr('500 Oracle Parkway, Redwood Shores, CA','(Apple|Park|Shores)') would be:

WHERE (INSTR('500 Oracle Parkway, Redwood Shores, CA', 'Apple') > 0
      OR
      INSTR('500 Oracle Parkway, Redwood Shores, CA', 'Park') > 0
      OR
      INSTR('500 Oracle Parkway, Redwood Shores, CA', 'Shores') > 0)

Depending on your needs, full text search functionality might be more towards what you want?

Obviously without regexp there won't be such an elegant solution, unless you write your own PL/SQL function that does the same job. Otherwise you would have to do something like this:

with data as (select '500 Oracle Parkway, Redwood Shores, CA' string from dual)
select nvl(min(pos),0) from
( select instr(data.string, 'Apple') pos
  union all
  select instr(data.string, 'Park') pos
  union all
  select instr(data.string, 'Shores') pos
)
where pos > 0;